The present invention relates to an apparatus for automatically diagnosing a state of operation of various valve devices for controlling fluids of high temperatures such as steam in, for example, a steam turbine system and gas in, for example, a gas turbine system.
In a steam turbine system, major valve devices such as main steam stop valve, reheat steam stop valve, intercept valve and turbine bypss valve are the essential and important constituents and, hence, are required to operate with a high reliability. From this point of view, it is a matter of great significance to continuously observe these valve devices and to detect signs of trouble, if any, at an early stage.
One of the most serious problems in such valve devices is a sticking of the valve. More specifically, the sticking of the valve is a phenomenon in which the initial smooth sliding between a movable part such as a valve rod and hydraulic piston and cooperating stationary part is lost to prevent sliding motion of the movable parts. Usually, the sticking of valve does not take place suddenly but is preceded by various symptoms such as unsmoothed sliding, vibration, chattering or the like. As the valve is left unrepaired, these symptoms are gradually developed to finally cause the the valve to stick. In order to prevent the sticking of a valve, therefore, it is essential to detect any symptom or extraordinary state of the valve and to take a suitable countermeasure at an early stage.
The observation and diagnosis of the major valve devices of turbine system in power generating plant or the like for detecting any symptom of a valve sticking has been made through a valve check usually conducted once a day. The valve test is executed by driving the valve from a fully open position to a fully close position and vice versa by a manual testing system, under the visual check by an operator. This conventional diagnostic method, however, is effective only to comparatively heavy or distinctive abnormality detectable by visual check but is quite ineffective for the detection of light or slight symptom of trouble.
Accordingly, it is a primary object of the invention to provide an apparatus for diagnosing valve devices in a turbine system, capable of accurately and sensitively detecting any trouble symptoms in the valve device.
To this end, according to one aspect of the invention, a diagnostic apparatus for diagnosing the state of a valve device in a turbine system includes a first sensor means for sensing the state of operation of the valve device, with a second sensor means being adapted to sense that the valve device is in the fully open position. A third sensor means is adapted to sense that the valve device is in the fully closed position, with a processing means being operatively connected to the first sensor means and being adapted to judge whether there is any abnormality in the operation of the valve device in accordance with the output from the first sensor means and to display the result of the judgement.
According to another aspect of the invention, a diagnosing the state of a valve device in a turbine system is accomplished by making a valve body of the valve device travel the fully stroke between a full open positon and a fully closed position; sensing at least one of the displacement of the valve body and the fluctuation of hydraulic pressure in a hydraulic cylinder for driving the valve body and obtaining data corresponding thereto, during the full stroke travelling of the valve body; processing the data and comparing the data with reference values representing the normal operating state of the valve device; and judging as to whether or not there is any abnormality in the valve device in accordance with the result of the comparison and displaying the result of the judgement.
The above and other objects, features and advantages of the invention will become more clear from the following descrption of the preferred embodiments when the same is read in conjunction with the accompanying drawings.